Vehicle engines commonly utilize cooling assemblies to remove excess heat from the engine and maintain an optimal operating temperature. The cooling assembly pumps a coolant through the engine and other components in order to control engine temperature. Heat generated within the engine and other components is absorbed by the coolant and dispersed into the surrounding atmosphere through the use of a radiator. In order to improve dispersal by the radiator, it is common to utilize fan assemblies to draw or force air past the radiator to assist in heat transfer.
It is not generally desirable for such fan assemblies to be run continuously. It is desirable to maintain a targeted coolant temperature; high fan speed is only needed during times of high heat generation. Additionally, continuous high speed operation when unnecessary places a non-required draw on the engine and thereby reduces efficiency. To compensate for this, present fan assemblies, such as “On-Off” style fan drives, utilize fan clutch assemblies that allow for the selective engagement of the fan to the engine such that the fans are engaged only when necessary. The fan clutch assemblies may be operated in a host of configurations including electronic, hydraulic and air-pressure actuated. It is common for these systems to be biased towards fan operation such that when failure occurs in the clutch assembly, the fan continuously operates to keep the engine cool.
Most On-Off fan drives operate at only one speed when actuated, namely input speed. In some situations, two-speed fan drives are desired. These drives often utilize an eddy-current mechanism to allow the fan drive to operate at a lower speed. The eddy-current assemblies provide for a much slower fan rotation when the fan is disengaged.
One concern with eddy-current clutches, or “On-Off” accessory drives combined with eddy-current drive assemblies, is the heat generated by the eddy-current drive, particularly heat generated in the flux rings. Not only can the heat reduce the effectiveness of the product, but the heat over time can expand and distort the flux ring, reducing both the durability and life of the product.
It would be highly beneficial if the flux ring for eddy-current clutch assemblies could be provided which had reduced temperatures and reduced stress during operation. This would provide a more durable, longer lasting and more effective eddy-current assembly.